Topic: 75 CB400F Starter Solenoid wiring question...

[txboarder]

Looking at my starter solenoid and some of the wiring diagrams I've been directed to (thanks again all for that), I have a quick question.  I'm doing a rewire on this project and the starter solenoid has two thick gauge wires going to the battery and the starter.  I get that.  I've got a yellow/red wire that goes to the starter switch, I get that.  I also have a green/red wire coming off of it that I've been told gets grounded to the frame.  The question I have with that is in the diagrams I've looked at show a black line that ties the run/stop switch, the black line from the regulator, black line from ignition switch and the solenoid but no ground except for the ground wire coming from the starter. 

Do I need to ground the solenoid or should I use that green/red line coming from it to tie in the run/stop switch etc...?

Thanks in advance for helping out an electrical nimwit.

[Bodi]

Yes you need the ground. Simplified wiring diagrams commonly simplify out important details.
The stock wiring harness protects you against using the electric start with the transmission in gear and clutch engaged. That's why the wire isn't plain green for ground, it goes to the clutch switch and the neutral switch in a stock system: it won't connect to ground and let the solenoid work unless one of those switches is closed.
Assuming you're not going to try starting it in gear and have the bike roar off into traffic or over a pedestrian, you can skip this safety system and just connect the wire to a frame ground.

[txboarder]

Good to know, yeah I've been riding plenty long enough to not try starting the bike in gear/when rolling/etc... So then that leaves me with where to tie in that black line (in the wiring diagram) to the solenoid.  Is that just supplying 12v so I should just tie it to where the battery (positive end) is tied to it?  Sorry for the ignorance.

[Bodi]

The small wires on the solenoid are for the magnet coil that pulls in the big switch which activates the starter motor.
Put battery voltage across those small wires and the starter will crank.
So you need to connect one wire through a push button start switch. It doesn't exactly matter whether you connect one to ground and switch the power, or the other way around. I prefer to switch power but that's just me.

I don't have your diagram and generally hate all wiring diagrams except the honest Honda diagram for your model and year. There are simplified wiring schematics for wiring a bike from scratch that are good for that purpose, but working on an OEM harness and using a any diagram except the Honda one is just pissing into a hurricane wind.

The 400F switches power to the solenoid coil, through the switchpod starter button. The ground isn't connected directly, I described that already. Honda CB400F black (no stripe) wires are always and only ignition power - battery power but fused plus switched on when the keyswitch is ON. There is no way a black wire connects directly to the solenoid coil. Your diagram is very wrong or you're misreading it.